Fluid driving device

ABSTRACT

A fluid driving device includes a vibration unit, a signal transmission layer, a piezoelectric element, and a plane unit. The signal transmission layer includes a first conductive zone and a second conductive zone. The piezoelectric element includes a first electrode and a second electrode electrically isolated from each other. The first electrode of the piezoelectric element is electrically connected to the first conductive zone of the signal transmission layer, and the second electrode of the piezoelectric element is electrically connected to the second conductive zone of the signal transmission layer. The plane unit has at least one hole. The signal transmission layer, the piezoelectric element, and the plane unit are located at one side of the vibration unit and sequentially stacked with each other.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a divisional of and claims priority to U.S. patentapplication Ser. No. 16/535,089 filed on Aug. 8, 2019, which claims thepriority benefit of Taiwan application serial no. 107128142, filed onAug. 13, 2018. The entirety of the above-mentioned patent applicationsare hereby incorporated in their entireties herein and made part of thisspecification by reference.

BACKGROUND Technical Field

The disclosure relates to a fluid driving device, and more particularlyto a fluid driving device whose signal transmission layer electricallyconnected to a piezoelectric element can be better protected.

Description of Related Art

A piezoelectric pump is a new type of fluid driver, which does notrequire any additional driving motor and can deform a piezoelectricvibrator only by an inverse piezoelectric effect of piezoelectricceramics, and fluid output can be realized due to the volume change ofthe pump chamber resulting from said deformation, or fluids can betransported through vibration of the piezoelectric vibrator. Therefore,piezoelectric pumps have gradually replaced traditional pumps and arewidely used in electronics, biomedical, aerospace, automotive, andpetrochemical industries.

In general, a piezoelectric pump is composed of a piezoelectric elementand a pump body. When electricity is supplied to the piezoelectricelement, the piezoelectric element is radially compressed due to anelectric field and is subject to internal tensile stress and is thenbent and deformed. When the piezoelectric element is bent in a positivedirection, the volume of the chamber of the pump body (hereinafterreferred to as the pump chamber) is increased, so that the pressure inthe pump chamber is reduced to allow fluid to flow into the pump chamberfrom the inlet. On the other hand, when the piezoelectric element isbent in a reverse direction, the volume of the pump chamber is reduced,so that the pressure in the pump chamber is increased, and that thefluid in the pump chamber is squeezed and discharged from the outlet. Atpresent, the circuit structure used to supply electricity to thepiezoelectric element is often a multi-layer structure and is locatedoutside the pump body; thus, the overall volume is large, and thestructure may be easily damaged.

SUMMARY

The disclosure provides a fluid driving device whose signal transmissionlayer electrically connected to a piezoelectric element can be betterprotected.

In an embodiment of the disclosure, a fluid driving device includes avibration unit, a signal transmission layer, a piezoelectric element,and a plane unit. The signal transmission layer includes a firstconductive zone and a second conductive zone. The piezoelectric elementincludes a first electrode and a second electrode electrically isolatedfrom each other. The first electrode of the piezoelectric element iselectrically connected to the first conductive zone of the signaltransmission layer, and the second electrode of the piezoelectricelement is electrically connected to the second conductive zone of thesignal transmission layer. The plane unit has at least one hole. Thesignal transmission layer, the piezoelectric element, and the plane unitare located at one side of the vibration unit and sequentially stackedwith each other.

According to an embodiment of the disclosure, the fluid driving devicefurther includes a transmission unit located between the vibration unitand the piezoelectric element, and the transmission unit is a flexibleprinted circuit board (FPCB).

According to an embodiment of the disclosure, the fluid driving devicefurther includes a frame and a protrusion. The vibration unit includes afirst central zone and a first peripheral zone, and the frame isdisposed between the first peripheral zone and the plane unit. Theprotrusion is disposed at a location corresponding to the at least onehole and between the first central zone and the plane unit and protrudestoward the at least one hole, and a surface of the frame facing theplane unit is coplanar with a surface of the protrusion facing the planeunit.

According to an embodiment of the disclosure, the transmission unitincludes a second central zone corresponding to the piezoelectricelement and a second peripheral zone located outside the second centralzone, the piezoelectric element is fixed to the second central zone ofthe transmission unit, and the frame is fixed to the second peripheralzone of the transmission unit.

According to an embodiment of the disclosure, the frame is fixed to thefirst peripheral zone of the vibration unit.

According to an embodiment of the disclosure, the piezoelectric elementincludes a through hole, and the protrusion passes through the throughhole.

According to an embodiment of the disclosure, the transmission unitincludes an opening corresponding to the through hole, and theprotrusion passes through the opening and is fixed to the first centralzone of the vibration unit.

According to an embodiment of the disclosure, the fluid driving devicefurther includes a protrusion. The vibration unit includes a firstcentral zone and a first peripheral zone, the protrusion is disposed ata location corresponding to the at least one hole and between the firstcentral zone and the plane unit and protrudes toward the at least onehole, a thickness of the first peripheral zone is greater than athickness of the first central zone, and a surface of the firstperipheral zone facing the plane unit is coplanar with a surface of theprotrusion facing the plane unit.

According to an embodiment of the disclosure, the protrusion of thefluid driving device is located on a surface of the piezoelectricelement facing the plane unit.

According to an embodiment of the disclosure, the fluid driving devicefurther includes a support member that includes a third central zone anda third peripheral zone, the third central zone of the support member isdisposed between the piezoelectric element and the plane unit and formsa protrusion corresponding to the at least one hole and protrudingtoward the at least one hole, and the third peripheral zone of thesupport member is disposed between a first peripheral zone of thevibration unit and the plane unit.

According to an embodiment of the disclosure, the fluid driving devicefurther includes a fluid guiding member, the plane unit is locatedbetween the piezoelectric element and the fluid guiding member, and thefluid guiding member includes at least one through hole.

In view of the above, the signal transmission layer, the piezoelectricelement, and the plane unit of the fluid driving device provided in thedisclosure are respectively located on the same side of the vibrationunit and are sequentially stacked. The signal transmission layerconfigured to be electrically connected to the first electrode and thesecond electrode of the piezoelectric element is located between thevibration unit and the plane unit; that is, the signal transmissionlayer is formed inside the fluid driving device and can be betterprotected.

To make the above features and advantages provided in one or more of theembodiments of the disclosure more comprehensible, several embodimentsaccompanied with drawings are described in detail as follows.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings are included to provide a furtherunderstanding of the disclosure, and are incorporated in and constitutea part of this specification. The drawings illustrate embodiments of thedisclosure and, together with the description, serve to explain theprinciples described herein.

FIG. 1 is a schematic view of a fluid driving device according to afirst embodiment of the disclosure.

FIG. 2 is a schematic view of FIG. 1 at another view angle.

FIG. 3 is a schematic exploded view of FIG. 1 .

FIG. 4 is a schematic exploded view of FIG. 2 .

FIG. 5 is a schematic cross-sectional view illustrating the fluiddriving device depicted in FIG. 1 .

FIG. 6 is a schematic cross-sectional view of a fluid driving deviceaccording to a second embodiment of the disclosure.

FIG. 7 is a schematic cross-sectional view of a fluid driving deviceaccording to a third embodiment of the disclosure.

FIG. 8 is a schematic cross-sectional view of a fluid driving deviceaccording to a fourth embodiment of the disclosure.

FIG. 9 is a schematic exploded view of a fluid driving device accordingto a fifth embodiment of the disclosure.

FIG. 10 is a schematic view of FIG. 9 at another view angle.

FIG. 11 is a schematic cross-sectional view illustrating the fluiddriving device depicted in FIG. 9 .

DESCRIPTION OF THE EMBODIMENTS

FIG. 1 is a schematic view of a fluid driving device according to afirst embodiment of the disclosure. FIG. 2 is a schematic view of FIG. 1at another view angle. FIG. 3 is a schematic exploded view of FIG. 1 .FIG. 4 is a schematic exploded view of FIG. 2. FIG. 5 is a schematiccross-sectional view illustrating the fluid driving device depicted inFIG. 1 . With reference to FIG. 1 to FIG. 5 , the fluid driving device100 provided in the embodiment includes a vibration unit 110, a signaltransmission layer 145, a piezoelectric element 130, and a plane unit160. The fluid driving device 100 will be described in detail below.

With reference to FIG. 3 and FIG. 4 , in the present embodiment, thevibration unit 110 includes a first central zone 112, a first peripheralzone 114, and a plurality of first connection zones 116 connected to thefirst central zone 112 and the first peripheral zone 114. The firstcentral zone 112 is movable relative to the first peripheral zone 114.In addition, in the embodiment, the material of the vibration unit 110may include a metal or an alloy and has a flexible property, but thematerial of the vibration unit 110 is not limited thereto. In otherembodiments, the vibration unit 110 can also be made of flexible rubber,silicone, or other non-metallic materials.

In the present embodiment, the piezoelectric element 130 has a firstsurface 132 (marked in FIG. 3 ) and a second surface 133 (marked in FIG.4 ), and the first surface 132 of the piezoelectric element 130 facesthe vibration unit 110. In the present embodiment, the piezoelectricelement 130 includes a first electrode 134 and a second electrode 138that are located on the first surface 132 and are electrically isolatedfrom each other. One of the first electrode 134 and the second electrode138 is a positive electrode, and the other is a negative electrode. Inaddition, in the embodiment, the shape of the piezoelectric element 130may be a sheet shape or an arbitrary geometric shape, and the outercontour of the piezoelectric element 130 may be an arc, a polygon, arectangle, and so on. The shape of the piezoelectric element 130 is notlimited in the disclosure.

As shown in FIG. 4 , in the present embodiment, the signal transmissionlayer 145 includes a first transmission zone 149 and a secondtransmission zone 148 that are electrically isolated. More specifically,in the present embodiment, the fluid driving device 100 further includesa transmission unit 140 located between the piezoelectric element 130and the vibration unit 110. The transmission unit 140 is a flexibleprinted circuit board (FPCB). The transmission unit 140 includes asecond central zone 141 surrounded by a plurality of slots 142 andcorresponding to the piezoelectric element 130 and a second peripheralzone 143 located outside the second central zone 141. The piezoelectricelement 130 is fixed to the second central zone 141 of the transmissionunit 140. A first transmission zone 149 and a second transmission zone148 are formed on the transmission unit 140, respectively. The firsttransmission zone 149 and the second transmission zone 148 on thetransmission unit 140 are electrically isolated and insulated from eachother so as to be not electrically connected to each other. Morespecifically, the first transmission zone 149 and the secondtransmission zone 148 extend to the second central zone 141 of thetransmission unit 140, respectively, and are connected to a firstconductive zone 147 and a second conductive zone 146 located in thesecond central zone 141.

With reference to FIG. 3 and FIG. 4 together, in the present embodiment,the first electrode 134 of the piezoelectric element 130 (marked in FIG.3 ) is electrically connected to the first transmission zone 149 (markedin FIG. 4 ) of the signal transmission layer 145 through the firstconductive zone 147, and the second electrode 138 of the piezoelectricelement 130 (marked in FIG. 3 ) is electrically connected to the secondtransmission zone 148 (marked in FIG. 4 ) of the signal transmissionlayer 145 through the second conductive zone 146.

Certainly, in other embodiments, the first transmission zone 149 and thesecond transmission zone 148 may also be two general-purpose wires ormay be directly connected to the first electrode 134 and the secondelectrode 138 of the piezoelectric element 130, and the firsttransmission zone 149 and the second transmission zone 148 are notnecessarily formed on the transmission unit 140. In addition, the firsttransmission zone 149 and the second transmission zone 148 are notnecessarily formed in the same layer; as long as the first transmissionzone 149 and the second transmission zone 148 are electrically connectedto the first electrode 134 and the second electrode 138 of thepiezoelectric element 130, the structure of these zones is not limitedto the structure described above.

In the present embodiment, the plane unit 160 is a valve plate, but theform of the plane unit 160 is not limited thereto. The plane unit 160includes three arc-shaped slots 163 that surround a circular fourthcentral zone 162 and distinguish a fourth peripheral zone 164 outsidethe fourth central zone 162. The location of the fourth central zone 162corresponds to the location of the piezoelectric element 130. In thepresent embodiment, the plane unit 160 further includes a hole 166formed in the fourth central zone 162. In other embodiments, the numberand the shape of the slots 163 of the plane unit 160 should not beconstrued as limitations. Besides, the material of the plane unit 160may include metal or a non-conductive material, which is slightlyflexible, but the material of the plane unit 160 should not be limitedto the material provided herein.

According to the present embodiment, note that the fluid driving device100 further includes a frame 120 and a protrusion 155. The frame 120 isdisposed between the first peripheral zone 114 of the vibration unit 110and the plane unit 160. More specifically, in the present embodiment,the frame 120 is fixed between the second peripheral zone 143 of thetransmission unit 140 and the fourth peripheral zone 164 of the planeunit 160. The protrusion 155 is disposed between the first central zone112 of the vibration unit 110 and the fourth central zone 162 of theplane unit 160. As shown in FIG. 5 , in the present embodiment, theprotrusion 155 is located on a surface of the piezoelectric element 130facing the plane unit 160, and the protrusion 155 protrudes toward thehole 166.

As shown in FIG. 5 , in the present embodiment, the protrusion 155 islocated on a surface of the piezoelectric element 130 facing the planeunit 160, and the protrusion 155 protrudes toward the hole 166. Besides,in the present embodiment, it can be observed from FIG. 5 that a surfaceof the frame 120 facing the plane unit 160 is coplanar with a surface ofthe protrusion 155 facing the plane unit 160. As such, after the fluiddriving device 100 is completely assembled, the protrusion 155 can pushagainst a portion of the plane unit 160 near the hole 166, so as toensure that at a certain moment of actuation (e.g., at the time shown inFIG. 5 ), the protrusion 155 pushes against the hole 166, such thatfluid (not shown) does not pass through the hole 166. In thisembodiment, the frame 120 and the protrusion 155 may be made of metal,ceramics, plastic, etc., and the types of the materials of the frame 120and the protrusion 155 are not limited in the disclosure.

In addition, as shown in FIG. 3 , in the present embodiment, the fluiddriving device 100 further includes a fluid guiding member 170, and theplane unit 160 is located between the piezoelectric element 130 and thefluid guiding member 170. In this embodiment, the fluid guiding member170 includes a fifth central zone 172 surrounded by three grooves 175and corresponding to the piezoelectric element 130, a fifth peripheralzone 174 located outside the fifth central zone 172, three through holes176 penetrating the fluid guiding member 170, and three flow paths 178respectively communicating with the three through holes 176. Certainly,the number of the grooves 175, the through holes 176, and the low paths178 of the fluid guiding member 170 are not limited thereto.

In the present embodiment, the fifth peripheral zone 174 of the fluidguiding member 170 is attached to the fourth peripheral zone 164 of theplane unit 160, and the fourth central zone 162 of the plane unit 160 ismovable relative to the fourth peripheral zone 164. Besides, in thisembodiment, the material of the fluid guiding member 170 may includemetal or an alloy, which should however not be construed as a limitationin the disclosure.

In the present embodiment, note that the transmission unit 140 havingthe signal transmission layer 145, the piezoelectric element 130, andthe plane unit 160 are located at the same side of the vibration unit110 and are sequentially stacked together. That is, in the presentembodiment, the transmission unit 140 having the signal transmissionlayer 145 and the piezoelectric element 130 are located between thevibration unit 110 and the plane unit 160. Since the signal transmissionlayer 145 is mainly formed within the fluid driving device 100, thesignal transmission layer 145 of the fluid driving device 100 providedin the present embodiment can be better protected.

In the fluid driving device 100 provided in the present embodiment, thesignal transmission layer 145 electrically connected to thepiezoelectric element 130 is disposed on one single transmission unit140 located between the vibration unit 110 and the piezoelectric element130. Since the signal transmission layer 145 is formed on one singletransmission unit 140, the overall thickness of the fluid driving device100 provided in the present embodiment is smaller than that of theconventional fluid driving device having a plurality of signaltransmission layers, and the fluid driving device 100 provided in thepresent embodiment can be easily assembled.

Other types of fluid driving devices 100 a, 100 b, and 100 c will bedescribed below. The same or similar elements provided in the followingembodiment and the previous embodiment will be denoted by the same orsimilar reference numerals and will not be described again, but the maindifferences between these embodiments will be explained below.

FIG. 6 is a schematic cross-sectional view of a fluid driving deviceaccording to a second embodiment of the disclosure. With reference toFIG. 6 , the main difference between the fluid driving device 100 aprovided in the present embodiment and the fluid driving device 100provided in the previous embodiment (e.g., shown in FIG. 5 ) is that thethickness of the frame 120 is substantially the same as the sum of thethickness of the piezoelectric element 130 and the thickness of theprotrusion 155 in the previous embodiment as shown in FIG. 5 .

In the present embodiment as shown in FIG. 6 , the thickness of theframe 120 is substantially the same as the thickness of thepiezoelectric element 130. Besides, in the present embodiment, the fluiddriving device 100 a further includes a support member 150 that includesa third central zone and a third peripheral zone 152. The third centralzone of the support member 150 is disposed between the piezoelectricelement 130 and the plane unit 160 as a protrusion 155 corresponding tothe hole 166 and protruding toward the hole 166. The third peripheralzone 152 of the support member 150 is disposed between the vibrationunit 110 and the plane unit 160. More specifically, the third peripheralzone 152 of the support member 150 is located between the frame 120 andthe plane unit 160.

In this embodiment, the support member 150 may be made of metal,ceramics, plastic, etc., and the types of the materials of the supportmember 150 are not limited in the disclosure. In this embodiment, thethird central zone (i.e., the protrusion 155) and the third peripheralzone 152 of the support member 150 can be made of the same object, so asto ensure that the thickness of the third central zone (i.e., theprotrusion 155) is the same as the thickness of the third peripheralzone 152. This not only guarantees the flatness of the fluid drivingdevice 100 a but also simplifies the fabrication of the fluid drivingdevice 100 a.

FIG. 7 is a schematic cross-sectional view of a fluid driving deviceaccording to a third embodiment of the disclosure. The frame is fixed tothe first peripheral zone of the vibration unit. With reference to FIG.7 , the main difference between the fluid driving device 100 b providedin the present embodiment and the fluid driving device 100 provided inthe embodiment shown in FIG. 5 lies in that the distribution area of theframe 120 corresponds to the distribution area of the second peripheralzone 143 of the transmission unit 140 in the embodiment shown in FIG. 5. That is, in the previous embodiment, the frame 120 is stacked in thesecond peripheral zone 143 of the transmission unit 140.

In the present embodiment, an outer contour of the second peripheralzone 143 of the transmission unit 140 b is smaller than the innercontour of the frame 120 b, and the transmission unit 140 b is locatedwithin the range of the frame 120 b. In the present embodiment, it canbe observed from FIG. 7 that the frame 120 b and the second peripheralzone 143 of the transmission unit 140 b are in contact with thevibration unit 110, respectively. Therefore, the second peripheral zone143 of the transmission unit 140 b does not overlap the frame 120 b.

In the present embodiment as shown in FIG. 7 , the thickness of theframe 120 b is substantially the same as the sum of the thickness of thetransmission unit 140 b, the thickness of the piezoelectric element 130,and the thickness of the protrusion 155. That is, a surface of the frame120 b facing the plane unit 160 is coplanar with a surface of theprotrusion 155 facing the plane unit 160. As such, after the fluiddriving device 100 is completely assembled, the protrusion 155 can pushagainst a portion of the plane unit 160 near the hole 166, so as toensure that at a certain moment of actuation (e.g., at the time shown inFIG. 5 ), the protrusion 155 pushes against the hole 166, such thatfluid (not shown) does not pass through the hole 166.

FIG. 8 is a schematic cross-sectional view of a fluid driving deviceaccording to a fourth embodiment of the disclosure. With reference toFIG. 8 , the main difference between the fluid driving device 100 cprovided in the present embodiment and the fluid driving device 100 bprovided in the embodiment shown in FIG. 7 lies in that the thickness ofthe first peripheral zone 114 c of the vibration unit 110 c is greaterthan the thickness of the first central zone 112. More specifically, inthe present embodiment, the vibration unit 110 c is similar to thecombination of the vibration unit 110 and the frame 120 b depicted inFIG. 7 .

In the present embodiment, a surface of the first peripheral zone 114 cof the vibration unit 110 c facing the plane unit 160 is coplanar with asurface of the protrusion 155 facing the plane unit 160. As such, afterthe fluid driving device 100 c is completely assembled, the protrusion155 can push against a portion of the plane unit 160 near the hole 166,so as to ensure that at a certain moment of actuation (e.g., at the timeshown in FIG. 5 ), the protrusion 155 pushes against the hole 166, suchthat fluid (not shown) does not pass through the hole 166.

FIG. 9 is a schematic exploded view of a fluid driving device accordingto a fifth embodiment of the disclosure. FIG. 10 is a schematic view ofFIG. 9 at another view angle. FIG. 11 is a schematic cross-sectionalview illustrating the fluid driving device depicted in FIG. 9 . Withreference to FIG. 9 to FIG. 11 , the difference between the fluiddriving device 100 d provided in the present embodiment and the fluiddriving device 100 b provided in the embodiment shown in FIG. 7 lies inthat the second central zone 141 of the transmission unit 140 b providedin the embodiment shown in FIG. 7 does not have any opening that allowsthe protrusion 155 to pass through, and the piezoelectric element doesnot have any through hole that allows the protrusion 155 to passthrough.

As shown in FIG. 9 , in the present embodiment, the piezoelectricelement 130 d has a ring shape and includes a through hole 131. Thetransmission unit 140 d includes an opening 144 corresponding to thethrough hole 131. The protrusion 155 passes through the through hole 131of the piezoelectric element 130 d and the opening 144 of thetransmission unit 140 d and is fixed to the first central zone 112 ofthe vibration unit 110.

As shown in FIG. 11 , in this embodiment, the thickness of the frame 120d is substantially the same as the thickness of the protrusion 155, andthe frame 120 and the protrusion 155 can be made of the same object,which simplifies the manufacturing process. Besides, a lower surface ofthe frame 120 d can be ensured to be aligned to a lower surface of theprotrusion 155, thus leading to a relatively small tolerance. Moreover,as shown in FIG. 11 and provided in the embodiment, the central locationof the fluid driving device 100 d (e.g., a location between the firstcentral zone 112 of the vibration unit 110 in FIG. 9 and the fourthcentral zone 162 of the valve plate 160) can be said to be the primaryfunctional zone of the fluid driving device 100 d. According to thepresent embodiment, since the first central zone 112 of the vibrationunit 110 and the fourth central zone 162 of the plane unit 160 areseparated only by the protrusion 155, the number of components at thecentral location of the fluid driving device 100 d is small.Accordingly, the fluid driving device 100 d has good precision.

To sum up, the signal transmission layer, the piezoelectric element, andthe plane unit of the fluid driving device provided in the disclosureare respectively located on the same side of the vibration unit and aresequentially stacked. The signal transmission layer configured to beelectrically connected to the first electrode and the second electrodeof the piezoelectric element is located between the vibration unit andthe plane unit; that is, the signal transmission layer is mostly formedinside the fluid driving device and can be better protected. Inaddition, in an embodiment, the signal transmission layer is formed inone layer and can be formed at the same transmission unit, for instance.Thereby, the number of components of the fluid driving device isrelatively mall, the number of layers of the fluid driving device isalso small, the assembling process is relatively simple and convenient,and the overall tolerance can be reduced.

Although the disclosure has been disclosed in the above embodiments, itis not intended to limit the disclosure, and any one of ordinary skillin the art can make some changes and refinements without departing fromthe spirit and scope of the disclosure. The scope of the disclosure isdefined by the scope of the appended claims.

What is claimed is:
 1. A fluid driving device comprising: a vibrationunit; a signal transmission layer comprising a first conductive zone anda second conductive zone; a piezoelectric element comprising a firstelectrode and a second electrode electrically isolated from each other,the first electrode of the piezoelectric element being electricallyconnected to the first conductive zone of the signal transmission layer,the second electrode of the piezoelectric element being electricallyconnected to the second conductive zone of the signal transmissionlayer; and a plane unit having at least one hole, the signaltransmission layer, the piezoelectric element, and the plane unit beingrespectively located on one side of the vibration unit and sequentiallystacked together; a transmission unit located between the vibration unitand the piezoelectric element, the transmission unit being a flexibleprinted circuit board; a frame, wherein the vibration unit includes afirst central zone and a first peripheral zone, and the frame isdisposed between the first peripheral zone and the plane unit; aprotrusion disposed at a location corresponding to the at least one holeand between the first central zone and the plane unit and protrudingtoward the at least one hole, wherein a surface of the frame facing theplane unit is coplanar with a surface of the protrusion facing the planeunit; wherein the frame is fixed to the first peripheral zone of thevibration unit.
 2. The fluid driving device of claim 1, wherein thepiezoelectric element comprises a through hole, and the protrusionpasses through the through hole.
 3. The fluid driving device of claim 2,wherein the transmission unit includes an opening corresponding to thethrough hole, the protrusion passes through the opening and is fixed tothe first central zone of the vibration unit.
 4. The fluid drivingdevice of claim 1, wherein a thickness of the first peripheral zonebeing greater than a thickness of the first central zone.
 5. The fluiddriving device of claim 4, wherein the protrusion is located on asurface of the piezoelectric element facing the plane unit.